A t-shirt mockup generator takes your design file, fits it into a print area drawn on a shirt photo, bends it to follow the fabric, and lays the photo's own shadows and highlights over it so the ink looks printed rather than pasted on. Almost every bad mockup comes from one of those steps going wrong, so knowing them tells you exactly what to check before an image goes into your listing.
This guide is for sellers who use an online t shirt mockup generator, free or built into a tool, and want listing photos that look like the shirt the buyer will receive. The first photo is what buyers see in search results, so a mockup that looks fake can lose you the click before anyone reads your title.
Step 1: the generator reads your file
Everything starts with the file you upload. A transparent PNG lets the shirt show through every empty area of the design. A JPEG cannot do that: it does not support transparency, so transparent areas can print as white (Printful file guide), and on a mockup they show up as a white box around your art. Our guide to exporting a transparent PNG shows how to avoid it.
Resolution matters too. The generator scales your file to fit the print area, and a small file stretched across a chest-sized area turns soft at the edges. A file made at print size and at the 300 DPI that Printify recommends for PNG and JPEG files (Printify file requirements) has detail to spare.
Step 2: it places the design in a print area
Every generator template has a box drawn on the photo that marks where the print goes. Your design is scaled to fit that box, so its proportions decide the result. A tall, narrow design fills the height and ends up narrow on the chest, while a wide design fills the width and sits short.
The box should match what your printer actually does, both in size and in distance below the collar. Print areas differ between providers. Printful's older standard front print area was 12 x 16 inches and it now uses 15 x 18 inches on select DTG tees (Printful print areas), and other providers differ, so check your provider's template. A mockup that shows a bigger or higher print than the one that ships is a promise you cannot keep. Our article on where to place a design on a shirt covers the collar distance.
Step 3: it warps the design to the fabric
Real shirts have folds, and a print on a fold bends with it. Generators reproduce this with a displacement map: a greyscale version of the shirt photo in which light and dark areas push the pixels of your design up or down, so straight lines curve over a wrinkle. Photoshop smart object mockups work on the same principle.
The strength of the warp is a balance. Too strong, and lettering wobbles as if the shirt were crumpled. Too weak, and the design sits flat on top of visible folds, which is the "sticker" look buyers notice even when they cannot name it.
Step 4: it adds shading, light and colour
After the warp, the generator blends the photo's shadows and highlights over the design. Usually the shadows are multiplied into the print, so the dark side of a fold darkens the ink as well as the fabric. Without that step, the print looks brighter than the shirt around it.
Dark shirts are harder. Multiplying shadows into white ink turns it grey and slightly see-through, while real white ink on a dark shirt is opaque. Good generators handle white differently on dark garments. Our guide to mockups for dark shirts shows what realistic white ink should look like.
Many generators also recolour one shirt photo into every colour you sell. That saves photography, but heathers and garment-dyed colours have texture that a flat recolour can lose, so check those colours one by one.
Step 5: objects in front, then the export
The last details separate a convincing mockup from a fake one. Anything in front of the shirt, such as a hand, a strap or hair, has to stay in front of the print too. Then the image is exported, and Etsy's rules take over: Etsy recommends listing photos "at least 2000 pixels or more" in width and height, says "transparent .png files are not supported", converts images to sRGB, and wants the first photo to be landscape or square (Etsy image guide). Since June 2026 you can preview listing thumbnails before publishing (Etsy updates), which is the moment to check the crop.
What to check in every mockup
| Check | What good looks like | What a problem looks like |
|---|---|---|
| Edges | Clean edges with no fringe | A white or coloured halo around the design |
| Size and position | Matches your printer's real placement | Print covering the whole torso, or sitting at the collar |
| Folds | Lines bend gently with the fabric | Lettering that wobbles, or flat art over a wrinkle |
| Shading | Shadows fall across the print | Print brighter than the shirt around it |
| Dark shirts | White ink looks solid | Grey, see-through white |
| Objects in front | Hands and straps cover the print | Print drawn over a hand |
| Thumbnail | Design readable in a square crop | Design cut off or too small to read |
Etsy's own checks point the same way. Its Search Visibility page looks for a primary photo that is clear, well lit and shows one finished product rather than a collage (Etsy search visibility), and Etsy asks you to position your image "so your subject is clear in all 3 views used across Etsy" (Etsy thumbnails). More warning signs are collected in mockup mistakes that make Etsy listings look fake.
How Alomations smart mockups place your design
In Alomations, smart mockups render your design onto product photos with real fabric folds, shading and light, and they are free to use. Objects in front of the design, such as a hand or a strap, stay in front. A front mockup can carry its own chest-logo spot, a background picker handles flat-lay shots, and a zoom (framing) control lets a product shot from far back fill more of the image. You can preview every colour and every side before the run, and download the results.
If you have your own photos, your own mockup library (on paid plans) lets you upload them, set the print area once and reuse it in every run. With your own photo loaded, Mockup Preview changes the shirt colour live, so one photo can show the colours you sell. Etsy allows 20 images and 2 videos per listing, and smart mockups count toward the 20. Our article on smart mockups in Alomations covers the feature in more detail.
Frequently asked questions
Why does my design look like a sticker on the mockup?
The warp or the shading is missing or too weak. Without a displacement map the design ignores the folds, and without shadows multiplied over it the print looks brighter than the fabric.
What size should a t-shirt mockup be for Etsy?
Etsy recommends listing photos at least 2000 pixels in width and height, and the first photo should be landscape or square. Export as JPG or PNG without transparency.
Can I use one shirt photo for every colour?
Yes, if the recolour looks right. Check heathers and textured colours separately, because a flat recolour can lose the texture buyers expect to see.
Is it a problem if the mockup looks better than the real shirt?
Yes. Etsy Purchase Protection does not cover a case where "The item doesn't match the listing description" (Etsy Purchase Protection), and a mockup brighter or larger than the real print invites exactly that complaint.
Make smart mockups of your next design with the Alomations free plan.